Universal bar adjustable to a curved or straight position



J. C. MORRIS UNIVERSAL BAR ADJUSTABLE TO A CURVED OR STRAIGHT POSITION Filed Dec. 26, 1963 Nov. 2, 1965 INVENTOR. Jbm/ c. MORE/5 4am J/M United States Patent 3,215,248 UNIVERSAL BAR ADJUSTABLE TO A CURVED 0R STRAIGHT POSITION John C. Morris, East Norwalk, Conn., assignor to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Filed Dec. 26, 1963, Ser. No. 333,290 3 Claims. '(Cl. 197-97) This invention relates to motion transmitting devices and more particularly to a motion transmitting device which receives an impulse from either one or more of plural selectively actuated mechanisms and utilizes said impulse to effect operation of either one or more other mechanisms.

The present invention finds ready application to business machines which are provided with a plurality of character and function keys. Actuation of a selected one of said keys usually initiates a cycle of operation of the business machine resulting in either the storage of a numerical value, the transfer of a selected character to another medium as by printing or punching, the performance of a mathematical computation, or some similar type of operation. During said cycle of operation various mechanisms of the business machine are rendered operative and inoperative in timed relationship with the actuation of said selected key. Said timed relationship is always irnportant and more often than not critical with an improper timing resulting in either an improper machine function or damage to the machine elements.

Some of said business machine mechanisms (such as escapements, ribbon feeds, ribbon vibrators, etc.) mus-t be operated each time any one of said plurality of character keys are actuated and it has therefore become common practice to provide a bar or bail universal to the levers or linkages associated with said plurality of keys, responsive to movement of any one of said levers or linkages,

and operative to actuate said mechanism, or mechanisms, in timed relationship with said key actuation. However, due to manufacturing tolerances inherent in the construction of said levers and linkages the portions thereof with which said universa bar coacts almost never form a straight line or curve of predetermined description, but instead form a curve of some description which cannot be predetermined and which is not identical for any two sets of levers or linkages. There is therefore usually a difference between the contour of the reacting surface of the universal bar and the contour defined by all of the coacting portions of the levers or linkages such that when same are assembled in juxtaposition one with respect to the other undesirable spaces appear between the surface of said universal bar and the contacting portions of some, if not most, of said levers or linkages. Such spaces cause a delayed coaction between said levers or linkages and said universal bar and undesirable impact of one against the other. This often results in improper operation of the machine, noise, and at times costly parts breakage.

Elimination of such undesirable spaces by constructing the levers or linkages for individual adjustment towards or away from said universal bar is not only expensive, in that it requires fabrication of additional parts and modification of the lever or linkage structure, but it is also inefficient in that it is difiicult to obtain access to the assembled mechanisms to effect an individual adjustment thereof. In the alternative, to construct the universal bar of flexible material and for unitary movement towards said levers or linkages to take up all of said spaces, unduly loads boththe universal bar and the levers or linkages and requires the development of additional power to drive the levers or linkages through their normal cycle of operation. One other common approach to this problem 3,215,248 Patented Nov. 2, 1965 is to construct the universal bar with a plurality of spring fingers (one for each lever or linkage) and to bend each spring finger and thereby establish a proper relationship between the spring finger and its associated lever or linkage. However here again access to the spring fingers, when the universal bar is assembled within the typewriter, is difficult to obtain and the bent fingers are in a stressed condition often resulting in breakage thereof and the necessity to replace the entire universal bar.

It is therefore an object of this invention to provide an improved motion transmitting device.

Another object is to provide an improved motion transmitting device which receives an impulse from either one or more of plural selectively actuated mechanisms and transmits said impulse to either one or more other mechanisms to effect operation thereof.

Another object is to provide a motion transmitting device which receives an impulse from either one or more of plural selectively actuated mechanisms and transmits said impulse to either one or more other mechanisms. to effect operation thereof, and which is readily adjustable to provide a uniform relationship between said motion transmitting device and said plural selectively actuated mechanisms.

Still another object is to provide an improved universal bar or bail.

Still another object is to provide an improved universal bar or bail for a business machine or the like.

A still further object is to provide a universal bar or bail for a business machine or the like which is readily adjustable to establish a uniform relationship between the universal bar and the coacting portion or portions of the business machine or the like.

The present invention involves a motion transmitting device having an elongated bail-like portion disposed for coaction with predetermined portions of a plurality of selectively actuated mechanisms, and contemplates providing said motion transmitting device with means to alter the contour of said bail-like portion to conform same to the contour described by said predetermined portions of said selectively actuated mechanisms to thereby establish a uniform relationship therebetween. In carrying out the invention, according to a preferred embodiment thereof, the motion transmitting device is constructed with a support member and a flexible reaction member interconnected by a plurality of individually adjustable mechanisms or elements which when adjusted, act on said fleXible reaction member to alter the contour thereof and maintain the members secured together and the contour as adjusted. Such motion transmitting device when properly adjusted also coacts with either one or more other mechanisms and, in response to operation of either one or more of said selectively actuated mechanisms, will effect operation of said other mechanism in a properly timed sequence with the operation of said one or more of the selectively actuated mechanisms.

Other objects and advantages of the invention in its details of construction and arrangement of parts will be.

apparent from a consideration of the following specification and accompanying drawing wherein:

FIG. 1 is a perspective view of a ribbon vibrator mechanism and type bar actuating linkage of the type commonly found in typewriters showing disposed therebetween a motion transmitting device, in the form of a universal bar, which embodies the present invention;

FIG. 2 is a fragmentary sectional view taken on line 2-2 of FIG. 1;

FIG. 3 is a fragmentary sectional view taken on line 33 of FIG. 2 showing the lower portion of additional.

type bar actuating linkages and the universal bar in adjusted condition;

FIG. 4 is a fragmentary sectional view similar to FIG. 3 but showing the universal bar in unadjusted condition; and

FIG. 5 is a fragmentary perspective view of the universal bar partially exploded to show the details of the adjusting mechanism.

For convenience the invention will be described as applied to a typewriter having a plurality of selectively actu ated character keys and a ribbon vibrator mechanism which is to be operated in timed sequence with the selective actuation of said character keys; it being understood nevertheless that without departing from the scope of this invention the subject motion transmitting device may be applied to other mechanisms of the typewriter (such as the ribbon feed, carriage escapement, etc.) or to other types of business machines (such as calculators, etc.), or to any machine having a plurality of selectively actuated mechanisms and either one or more other mechanisms which are to be operated in timed sequence with the operation of either one or more of said selectively actuated mechanisms.

With the reference to FIG. 1, the number generally designates a ribbon vibrator mechanism adapted for operation in timed sequence with the operation of a type bar linkage group 11 and coacting therewith to effect printing of a selected character upon a work sheet (not shown). In actuality a plurality of linkage groups 11 are disposed side-by-side one adjacent another in an array (FIG. 3) between the frames of the typewriter, the number thereof depending upon the number of characters provided with the typewriter, however, since all linkage groups 11 are of substantially identical construction only one complete linkage group 11 will be described hereinafter.

Each linkage group 11 includes a type bar bell crank 13 pivotally mounted at 15 to a bracket (not shown) and interconnected by a link 21 to a type bar 23 pivotally mounted on a wire rod 25. A roller 27 engaging type bar bell crank 13, is carried by an arm 29 which is associated with a predetermined character key (not shown). Operator actuation of said predetermined character key effects a lateral movement (to the right in FIG. 2) of arm 29 and thereby a clockwise pivoting movement about 15 (FIG. 2) of type bar bell crank 13. Link 21 (FIGS. 1 and 2) transmits the clockwise movement of type bar bell crank 13 to type bar 23 to move same from a rest position (FIG. 1) to a printing position (not shown). Appropriate springs (not shown) return type bar linkage group 11 to its unactuated condition (FIGS. 1 and 2).

A ribbon 31 (FIG. 1) is carried by ribbon vibrator mechanism 10 for movement thereby into the path traveled by type bar 23 when moving to said printing position to cooperate therewith and effect printing of a selected character, and for movement thereby out of said path of travel of type bar 23 to permit observation of the printed character. A carrier 35 (FIG. 1), formed with a pair of guides 37 for receiving ribbon 31, is pivotally connected to an arm 39 of a substantially U shaped ribbon actuator 41 rockably carried by a bracket 43 which is fixedly secured to the typewriter as at 45. An arm 47 of actuator 41 is formed with a slot 49 which receives a stud 51 carried by a rod 53 pivotally connected by a pin 55 to an arm 57 rockably mounted between the typewriter frames (not shown) as at 59. Clockwise rocking (FIG. 1) of arm 57 raises rod 53 and through the coaction of stud 51 with the sides of slot 49 effects a counterclockwise rocking (FIG. 1) of actuator 41 and an upward movement (FIG. 1) of ribbon carrier 35 to move ribbon 31 into the path of travel of type bar 23. Appropriate springs (not shown) return ribbon vibrator mechanism 10 to its unactuated condition (FIG. 1).

A slot 71, formed in rod 53, receives a stud 73 carried by a ribbon throw adjusting device 75 (FIG. 1) which is operator controlled to effect movement of stud 51 in slot 49 to thereby control the degree of counterclockwise rocking motion imparted to actuator 41 by a uniform movement of rod 53. Thusly the movement of ribbon carrier 35 is controlled to place a predetermined portion of ribbon 31 in the path of travel of type bar 23 as required when using either the red field or the black field of a bi-color ribbon, or to maintain ribbon 31 out of the path of travel of type bar 23 as required when typing stencils.

In addition to controlling the extent of movement 'of ribbon 31 into the path of travel of type bar 23 it is also necessary to control the time at which the movement of ribbon 31 is initiated and especially to control same so as to initiate ribbon movement in timed sequence with the operation of type bar 23. To that end a motion transmitting device in the form of a universal bar assembly 91 (FIGS. 1, 2 and 3) is disposed in juxtaposition with all type bar linkage groups 11 to receive an impulse from any one of said linkage groups 11, when actuated as described above, and to utilize said impulse to effect operation of ribbon vibrator mechanism 10.

A pin 93 (FIG. 1) connects an arm 95 (FIGS. 1 and 2), of universal bar assembly 91, to arm 57 of ribbon vibrator mechanism 10. A support ,rod 97, pivotally mounted between the side frames (not shown) of the typewriter and connected to arm 95 by appropriate securing means such as bolts 99 (FIG. 2), mounts a reaction member 111 through the intermediary of a plurality of adjusting mechanisms or fastening elements 113. Reaction member 111 is formed of resilient material and with a considerably greater plurality of spring fingers 115, each associated with a corresponding type bar bell crank 13 of a predetermined linkage group 11 and each disposed for coaction with a contact surface 117 (FIG. 2) of a heel 119 formed on said associated type bar bell crank 13. Adjusting mechanisms 113 are distributed in spaced relationship along the length of support rod 97 and reaction member 111 and interconnect one to the other. Each adjusting mechanism 113 (FIGS. 4 and 5) includes; a jacking screw 123 formed with external threads 125, an internal bore 127, an upper surface 129, and a nut-like screw operator and abutment 131 formed on the operating or lower end thereof; a retaining stud 133 formed with a shank portion 135 adapted to pass through bore 127 of jacking screw 123, a threaded end portion 137, and an enlarged head 139; and a lock nut 141 formed with threads 143 adapted to be threaded onto threaded portion 137 of retaining stud 133.

A plurality of internally threaded bores 151 (FIG. 5) are formed in support bar 97 in spaced relationship one with respect to the other and of a size adapting same to receive external threads of jacking screw 123. A plurality of apertures 153 (FIG. 5) areformed in reaction member 111 in spaced relationship one with respect to the other and with an internal diameter which is larger than the diameter of shank portion of retaining stud 133 and smaller than the outside diameter of threaded portion 125 of jacking screw 123.

In assembly of universal bar assembly 91 jacking screws 123 are threaded into bores 151 of support bar 97 and reaction member 111 is seated on upper surface 129 of jacking screws 123 so as to be flush with the upper surface of support bar 97. Retaining screws 133 are inserted through apertures 153 of reaction member 111 and bores 127 of jacking screws 123 until heads 139 thereof rest upon the upper surface of reaction member 111. Look nuts 141 are then threaded onto threaded portions 137 of retaining studs 133 to sandwich reaction member 111 between heads 139 of retaining studs 133 and upper surfaces 129 of jacking screws 123 and thereby to secure universal bar assembly 91 together as a unitary motion transmitting device.

It should be noted that when reaction member 111 is assembled to support bar 97, as described above, that the lower surface of reaction member 111 assumes a substantially planar contour (FIG. 4). It should be further noted that contact surfaces 117 of heel portions 119 of type bar bell cranks 13 do not assume a planar contour but instead that they describe an irregularly curved contour (FIG. 4). Said irregularly curved contour results from the normal variances incident to. the manufacture of mechanisms such as type bar linkage groups 11 and is different for each set of linkage groups 11. Furthermore since said differences cannot be calculated with any degree of assuredness it is impossible to predetermine the contour which contact surfaces 117 will describe.

A spring 165 (FIG. 1), secured to the typewriter frame as at 167, urges universal bar assembly 91 in the clockwise direction (FIG. 1) to move spring fingers 115 thereof into engagement with contact surfaces 117 of heel portions 119 of type bar bell cranks 13. At initial insertion of universal bar assembly 91 into the typewriter spring 165 will urge same in the clockwise direction (FIG. 1) until touching engagement is established betwen those bell cranks 13' having contact surfaces 117 which are disposed at the highest level and the associated spring fingers 115. The adjusting mechanisms 113 which are closest to said bell cranks 13 having the highest contact surfaces 117 are then adjusted by loosening lock nuts 141 as by operating on abutments 131 and rotating jacking screws 123 thereof so as to flex the adjacent section of reaction member 111. Flexure of reaction member 111 permits spring 165 toagain urge universal bar assembly 91 in the clockwise direction to move additional spring fingers 115 either closer to or into touching engagement with their respective contact surfaces 117. Lock nuts 141 may then be loosened more to permit additional adjustment of reaction member 111 or they may be tightened to secure reaction member 111 in its adjusted position.

Successive incremental adjustment of each adjusting mechanism 113, as described above, will therefore flex reaction member 111 in sections and permit alteration of the contour thereof to conform same as close as possible to the contour described by contact surfaces 117 (FIG. 5) and thereby establish a uniform relationship between linkage groups 11 and motion transmitting device 91. Said conformance of the contours of reaction member 111 and contact surfaces 117 will be evident upon either a visual examination of said contours or by observing the height to which ribbon 31 or ribbon carrier 35 is moved as each linkage group 11 is actuated.

Subsequent operation of a selected character key (not shown) results in a righthand movement (FIG. 2) of an associated arm 29 and roller 27 and a clockwise (FIG. 2) pivoting of type bar bell crank 13 engaged therewith to pull on link 21 and pivot type bar 23 from its rest position (FIG. 1) to a printing position. As type bar bell crank 13 pivots in the clockwise direction (FIG. 2) contact surface 117 of heel portion 119 thereof acts on its associated spring finger 115 and thereby on reaction member 111 to rock support bar 97 and arm 95 carried thereby in the counterclockwise direction (FIG. 1). Arm 57 (FIG. 1), rocked in the clockwise direction (FIG. 1) by the counterclockwise movement of arm 95 and support bar 97 pushes up (FIG. 1) on rod 53 which in turn through pin 51 and the coacting wall of slot 49 effects a clockwise pivoting (FIG. 1) of ribbon actuator 41 to raise ribbon carrier 35 and thereby move ribbon 31 into the path of travel of type bar 23 in proper time to coact therewith and effect a proper printing of the selected character. Appropriately disposed springs (not shown) return all the elements to their respective rest positions.

From the above description it will thus be seen that a novel and improved motion transmitting device has been provided, which device is simple in construction, etficient in operation, and readily adjusable to alter the contour thereof to conform same to the contour of a plurality of selectively actuated mechanisms with which said motion transmitting device is to coact. In this manner a uniform relationship is established between said motion transmitting device and said plurality of selectively aotuated mechanisms to insure a properly timed sequence of operation therebetween and between same and an other mechanism which coacts with said motion transmitting device and is to be operated in timed sequence with the operation of a selected one of said plurality of selectively actuated mechanisms.

It is understood that although I have shown the preferred form of my invention, that various modifications may be made in the details thereof without departing from its spirit as comprehended by the following claims.

I claim:

1. A business machine of the class described comprising (a) a plurality of selectively actuated mechanisms disposed in an array one adjacent another;

(h) each of said selectively actuated mechanisms including a contact surface, said contact surfaces in said array describing a curve;

(0) other mechanisms adapted to be operated in timed relationship with the operation of any one or more of said plurality of selectively actuated mechanisms;

(d) support means;

(e) pivot means mounting said support means intermediate said plurality of selectively actuated mechanisms and said other mechanisms;

(f) connection means interconnecting said support means and said other mechanisms to transfer pivoting motion of said support means to effect operation of said other mechanisms;

(g) reaction means formed of flexible material and with a plurality of spring fingers each coacting with a contact surface of a different one of said selectively actuated mechanisms;

said reaction means in response to actuation of either one or more of said plurality of selectively actuated means effecting a pivotal movement of said support means and thereby an operation of said other mechanisms; and" (h) adjusting means interconnecting said support means assembled with reaction means adjustably to alter the contour of said reaction means to conform same to said curve described by said contact surfaces and thereby establish a uniform relationship therebetween;

said adjusting means comprising a plurality of adjusting elements disposed in spaced relationship along said support means, each said adjusting element including (1) a jacking screw having an internal bore, ex-

ternal threads, an upper contact surface at one extremity thereof upon which said reaction means rests, and an abutment at the other extremity thereof;

(2) a retaining stud having a shank portion passing through said bore and terminating in a threaded portion, both said portions formed to a size permitting passage thereof through said bore of said jacking screw; and

(3) a lock nut formed with threads for engaging with the threaded portions of said retaining stud;

said support means having a plurality of spaced internally threaded bores adapted to receive the external threads of said jacking screws;

said reaction means including a plurality of spaced apertures larger in diameter than said shank portion of said retaining studs passing through said apertures and smaller in diameter than the outside diameter of said jacking screws; and

one each of said lock nuts being threaded on said retaining studs against said abutment to secure said reaction means to said jacking screws.

2. A motion transmitting device for a machine of the class described comprising (a) a support member of elongated configuration;

(b) a flexible reaction member of elongated configuration; and

(c) adjusting means interconnecting said reaction member to said supportmember and including a plurality of individually adjustable fastening elements distributed along the length of said support member .and reaction member configuration for altering the contour of said reaction member by flexing movement thereof toward and away from said support member, each fastening element including (1) a jacking screw threadably received in said support member and having an upper surface extendable above said support member and adapted to support said reaction member;

(2) a retaining stud adapted for passage through said reaction member and said jacking screw;

and

(3) a lock nut coacting with said retaining stud and said jacking screw to secure one to the other and to thereby secure said reaction member to said jacking screw.

3. A business machine of the class described comprising (a) a plurality of selectively actuated mechanisms;

(b) at least one other mechanism adapted to be operated in timed relationship with the actuation of any one of said plurality of selectively actuated mechanisms;

(c) a motion transmitting device coacting With said plurality ofselectively actuated mechanisms and said other mechanism and responsive to actuation of any one of said plurality of selectively actuated mechanisms to effect operation of said other mechanism; and

(d) adjusting means operable to change the contour of said motion transmitting device to establish a uniform relationship between said motion transmitting device and said plurality of selectively actuated mechanisms;

said motion transmitting device comprising (1) an elongated bar-like support member with a plurality of spaced and threaded apertures;

(2) a plurality of jacking members each formed with an internal bore, an external thread coacting with said threaded apertures in said support member, a contact at one extremity, and an enenlarged abutment at the other extremity;

(3) an elongated reaction member of flexible material formed with a plurality of spring fingers each coacting with a corresponding one of said plurality of selectively actuated mechanisms; said reaction member being seated on said jacking member contact and having a plurality of spaced apertures each having a diameter substantially equal to that of said jacking member internal bore, such aperture being in alignment with an internal bore of said jacking members;

(4) a retaining member for each of said jacking members and having a shank for passage through an aperture of said reaction member and the aligned internal bore of said jacking member, an enlarged head for resting on said reaction member, and a threaded end portion;

(5) a lock nut for each of said retaining members, said nut having threads coacting with said retaining member threaded ends to secure said retaining member to said jacking member with said reaction member disposed between said heads and said contacts.

References Cited by the Examiner UNITED STATES PATENTS 716,701 12/02 Gabrielson 197-97 X 1,119,644 12/ 14 Sargent et a1. 19797 1,347,632 7/20 Holden 19797 2,042,783 6/36 Hall.

2,155,997 4/39 Sterling 197-97 X 2,199,802 5/40 Leitz et al. 1 2,630,898 3/53 Hamilton 851 X ROBERT E. PULFREY, Primary Examiner. 

1. A BUSINESS MACHINE OF THE CLASS DESCRIBED COMPRISING (A) A PLURALITY OF SELECTIVELY ACTUATED MECHANISMS DISPOSED IN AN ARRAY ONE ADJACENT ANOTHER; (B) EACH OF SAID SELECTIVELY ACUTATED MECHANISMS INCLUDING A CONTACT SURFACE, SAID CONTACT SURFACES IN SAID ARRAY DESCRIBING A CURVE; (C) OTHER MECHANISMS ADAPTED TO BE OPERATED IN TIMED RELATIONSHIP WITH THE OPERATION OF ANY ONE OR MORE OF SAID PLURALITY OF SELECTIVELY ACTUATED MECHANISMS; (D) SUPPORT MEANS; (E) PIVOT MEANS MOUNTING SAID SUPPORT MEANS INTERMEDIATE SAID PLURALITY OF SELECTIVELY ACTUATED MECHANISMS AND SAID OTHER MECHANISMS; (F) CONNECTION MEANS INTERCONNECTING SAID SUPPORT MEANS AND SAID OTHER MECHANISMS TO TRANSFER PIVOTING MOTION OF SAID SUPPORT MEANS TO EFFECT OPERATION OF SAID OTHER MECHANISM; (G) REACTION MEANS FORMED OF FLEXIBLE MATERIAL AND WITH A PLURALITY OF SPRING FINGERS EACH COACTING WITH A CONTACT SURFACE OF A DIFFERENT ONE OF SAID SELECTIVELY ACTUATED MECHANISMS; SAID REACTION MEANS IN RESPONSE TO ACTUATION OF EITHER ONE OR MORE OF SAID PLURALITY OF SELECTIVELY ACTUATED MEANS EFFECTING A PIVOTAL MOVEMENT OF SAID SUPPORT MEANS AND THEREBY AN OPERATION OF SAID OTHER MECHANISMS; AND (H) ADJUSTING MEANS INTERCONNECTING SAID SUPPORT MEANS ASSEMBLED WITH REACTION MEANS ADJUSTABLY TO ALTER THE CONTOUR OF SAID REACTION MEANS TO COMFORM SAME TO SAID CURVE DESCRIBED BY SAID CONTACT SURFACES AND THEREBY ESTABLISH A UNIFORM RELATIONSHIP THEREBETWEEN; SAID ADJUSTING MEANS COMPRISING A PLURALITY OF ADJUSTING ELEMENTS DISPOSED IN SPACED RELATIONSHIP ALONG SAID SUPPORT MEANS, EACH SAID ADJUSTING ELEMENT INCLUDING (1) A JACKING SCREW HAVING AN INTERNAL BORE, EXTERNAL THREADS, AN UPPER CONTACT SURFACE AT ONE EXTREMITY THEREOF UPON WHICH SAID REACTION MEANS RESTS, AND AN ABUTMENT AT THE OTHER EXTREMITY THEREOF; (2) A RETAINING STUD HAVING A SHANK PORTION PASSING THROUGH SAID BORE AND, TERMINATING IN A THREADED PORTION, BOTH SAID PORTIONS FORMED TO A SIZE PERMITTING PASSAGE THEREOF THROUGH SAID BORE OF SAID JACKING SCREW; AND (3) A LOCK NUT FORMED WITH THREADS FOR ENGAGING WITH THE THREADED PORTIONS OF SAID RETAINING STUD; SAID SUPPORT MEANS HAVING A PLURALITY OF SPACED INTERNALLY THREADED BORES ADAPTED TO RECEIVE THE EXTERNAL THREADS OF SAID JACKING SCREWS; SAID REACTION MEANS INCLUDING A PLURALITY OF SPACED APERTURES LARGER IN DIAMETER THAN SAID SHANK PORTION OF SAID RETAINING STUDS PASSING THROUGH SAID APERTURES AND SMALLER IN DIAMETER THAN THE OUTSIDE DIAMETER OF SAID JACKING SCREWS; AND ONE EACH OF SAID LOCK NUTS BEING THREADED ON SAID RETAINING STUDS AGAINST SAID ABUTMENT TO SECURE SAID REACTION MEANS TO SAID JACKING SCREWS. 